Rozhen Observation Calendar

Which nights are best for a target over the coming weeks. The astronomy mark (darkness × altitude × Moon) is computed for every night; the weather and the overall mark exist only where Open-Meteo has a forecast (the next four days) or ERA5 history (past nights) — the rest is honestly blank.

Best nights for HD 189733: 12-30 (8), 12-31 (7), 01-01 (6), 01-02 (6), 01-03 (5) — by astronomy; check the weather when the night is within four days.

2028-12-30astronomy score per night — click a bar for that night2029-01-28

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-12-30 Sat	8	—	unknown	18:10–19:20 (marginal, 1.17 h)	71.1° 13:45	11.47	99%	124.4°
2028-12-31 Sun	7	—	unknown	18:45–19:15 (marginal, 0.5 h)	71.1° 13:40	11.46	100%	132.2°
2029-01-01 Mon	6	—	unknown	18:45–19:10 (marginal, 0.42 h)	71.1° 13:35	11.45	98%	137.8°
2029-01-02 Tue	6	—	unknown	18:10–18:40 (marginal, 0.5 h)	71.1° 13:35	11.44	94%	140.2°
2029-01-03 Wed	5	—	unknown	18:45–19:05 (marginal, 0.33 h)	71.1° 13:30	11.42	87%	138.4°
2029-01-04 Thu	4	—	unknown	18:45–19:00 (marginal, 0.25 h)	71.1° 13:25	11.41	78%	133.0°
2029-01-05 Fri	3	—	unknown	18:15–18:30 (marginal, 0.25 h)	71.1° 13:20	11.4	68%	125.0°
2029-01-06 Sat	2	—	unknown	18:15–18:25 (marginal, 0.17 h)	71.1° 13:20	11.38	57%	115.6°
2029-01-07 Sun	2	—	unknown	18:15–18:20 (marginal, 0.08 h)	71.1° 13:15	11.37	46%	105.3°
2029-01-08 Mon	1	—	unknown	—	71.1° 13:10	11.35	35%	94.6°
2029-01-09 Tue	1	—	unknown	—	71.1° 13:05	11.34	24%	84.0°
2029-01-10 Wed	1	—	unknown	—	71.1° 13:00	11.32	16%	73.6°
2029-01-11 Thu	1	—	unknown	—	71.1° 13:00	11.3	8%	63.7°
2029-01-12 Fri	0	—	unknown	—	71.1° 12:55	11.28	4%	54.8°
2029-01-13 Sat	0	—	unknown	—	71.1° 12:50	11.26	1%	47.4°
2029-01-14 Sun	0	—	unknown	—	71.1° 12:45	11.24	0%	42.2°
2029-01-15 Mon	0	—	unknown	—	71.1° 12:40	11.22	2%	39.9°
2029-01-16 Tue	0	—	unknown	—	71.1° 12:40	11.2	5%	40.8°
2029-01-17 Wed	0	—	unknown	—	71.1° 12:35	11.17	10%	44.7°
2029-01-18 Thu	0	—	unknown	—	71.1° 12:30	11.15	17%	50.6°
2029-01-19 Fri	0	—	unknown	—	71.1° 12:25	11.13	24%	57.9°
2029-01-20 Sat	0	—	unknown	—	71.1° 12:25	11.1	33%	66.0°
2029-01-21 Sun	0	—	unknown	—	71.1° 12:20	11.08	42%	74.6°
2029-01-22 Mon	0	—	unknown	—	71.1° 12:15	11.05	51%	83.7°
2029-01-23 Tue	0	—	unknown	—	71.1° 12:10	11.02	61%	92.9°
2029-01-24 Wed	0	—	unknown	—	71.1° 12:05	10.99	70%	102.3°
2029-01-25 Thu	0	—	unknown	—	71.1° 12:00	10.96	79%	111.7°
2029-01-26 Fri	0	—	unknown	—	71.1° 11:55	10.94	87%	120.8°
2029-01-27 Sat	1	—	unknown	—	71.1° 11:50	10.91	93%	129.2°
2029-01-28 Sun	1	—	unknown	—	71.1° 11:45	10.88	98%	135.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-12-30&days=30"
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&days=30&format=csv" -o m31-calendar.csv

One row per night: score_astronomy always, score_weather / score only where a forecast or history exists (null otherwise, with weather_source saying which), best window, dark hours, Moon illumination and separation, transit. 7–60 nights. Errors: 400 with invalid_date or target_unresolved. Results are cached for six hours; calculation version 2026-10-10.1.